Cinch direct mount 2X ring system

ABSTRACT

A cinch direct mount 2× ring system is disclosed. One embodiment discloses a chainring assembly having a drive side crank arm with a chainring assembly interface including a plurality of splines, a circumference, and an axial length. The chainring assembly includes a first chainring having a first outer diameter and a first center assembly shape. The chainring assembly includes a second chainring having a second outer diameter and a second center assembly shape, the second outer diameter being different than the first outer diameter. The chainring assembly also includes a fastener to couple the first chainring and the second chainring with the chainring assembly interface, such that at least one of the first center assembly shape or the second center assembly shape engages with the plurality of splines.

CROSS REFERENCE

This application claims priority to and is a Divisional of co-pendingU.S. patent application Ser. No. 15/953,903 filed on Apr. 16, 2018,entitled “Cinch Direct Mount 2× Ring System” by Evan Choltco-Devlin etal. and assigned to the assignee of the present application, thedisclosure of which is hereby incorporated herein by reference in itsentirety.

The application Ser. No. 15/953,903 claims priority to and benefit ofU.S. Provisional Patent Application No. 62/491,958 filed on Apr. 28,2017, entitled “Cinch Direct Mount 2× Ring System” by EvanCholtco-Devlin et al. and assigned to the assignee of the presentapplication, the disclosure of which is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Embodiments of the invention generally relate to a chainring assemblyfor a chain driven vehicle.

BACKGROUND

Traditional crank assemblies include one or more chainrings that areused to drive, via a chain, one or more sprockets coupled to an axle ofa wheel. Chainrings are liable to bend, break or wear down based on use.Moreover, it is not uncommon to need a different size of chainringdepending upon what type of terrain is being crossed or what maneuversare being performed. As such, chainring manufacture, design andimplementation are constantly being improved. However, as with almostall mechanical designs, a number of desirable features are incongruent.For example, going faster usually means a larger diameter chainring,while vehicle clearance calls for a smaller diameter chainring. As such,there is constant innovation and invention within the field of chainringassemblies, innovation and invention that requires more than simplesubstitution of parts in order to increase the desired performance whilereducing the detrimental downside associated therewith.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present invention are illustrated by way of example, andnot by way of limitation, in the accompanying drawings, wherein:

FIG. 1A is an exploded view of a crank assembly, in accordance with anembodiment.

FIG. 1B is a side view of a crank arm with a spline, in accordance withan embodiment.

FIG. 2A is an exploded view of a chainring assembly having all splinesengaged by each chainring, in accordance with an embodiment.

FIG. 2B is a cross-section view of the chainring assembly of FIG. 2A, inaccordance with an embodiment.

FIG. 3A is an exploded view of a chainring assembly having all splinesengaged by a first chainring, in accordance with an embodiment.

FIG. 3B is a cross-section view of the chainring assembly of FIG. 3A, inaccordance with an embodiment.

FIG. 4A is an exploded view of a chainring assembly having a firstcircumferential portion of splines engaged by each chainring togetherwith a remaining circumferential portion engaged only by one chainring,in accordance with an embodiment.

FIG. 4B is a cross-section view of the chainring assembly of FIG. 4A, inaccordance with an embodiment.

FIG. 5A is an exploded view of a chainring assembly having a firstcircumferential portion of splines engaged by a first chainring and aremaining circumferential portion engaged by a second chainring, inaccordance with an embodiment.

FIG. 5B is a cross-section view of the chainring assembly of FIG. 5A, inaccordance with an embodiment.

FIG. 6A is an exploded view of a chainring assembly having an entirecircumferential portion of splines engaged by a first chainring and aremaining axial space filled by a second chainring without the secondchainring engaging any portion of the splines, in accordance with anembodiment.

FIG. 6B is a cross-section view of the chainring assembly of FIG. 6A, inaccordance with an embodiment.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

DESCRIPTION OF EMBODIMENTS

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various embodiments of thepresent invention and is not intended to represent the only embodimentsin which the present invention is to be practiced. Each embodimentdescribed in this disclosure is provided merely as an example orillustration of the present invention, and should not necessarily beconstrued as preferred or advantageous over other embodiments. In someinstances, well known methods, procedures, and objects have not beendescribed in detail as not to unnecessarily obscure aspects of thepresent disclosure.

For purposes of the following discussion, the term “chainring” (orchainwheel) refers to one or more toothed components that are located atthe crank assembly of a vehicle (e.g., where the cranks and pedals arelocated). The chainring rotates in either a clockwise orcounterclockwise direction based on input from the rider provided via apedal (or crank).

The term “sprocket” refers to the one or more toothed components thatare found at the drive wheel of a vehicle (usually the rear wheel). Therotation of the one or more sprockets (in the appropriate direction)causes the drive wheel of the vehicle to rotate.

The term “roller chain” refers to the chain on a vehicle, such as abicycle, that fits into the teeth of the chainring and the teeth of thesprocket to form a mechanical connection between the two. Thus, as thechainring is rotated, usually by peddling or the like, movement of theroller chain occurs. The movement of the roller chain about thechainring and the sprocket causes a movement of the sprocket at thedrive wheel of the bicycle.

The amount of rotational movement of the sprocket depends upon the sizeratio between the chainring and the sprocket. For example, if the ratiois 1:1, (e.g., the chainring and sprocket are the same tooth count) arotation of the chainring will cause the roller chain to rotate thesprocket the same amount. However, if the ratio is 2:1, (e.g., thechainring has twice the tooth count of the sprocket) a rotation of thechainring will cause the roller chain to rotate the sprocket twice asmuch. For example, a full revolution of the chainring will result in twofull rotations of the sprocket.

Overview

In one embodiment of the chainring assembly described herein create achainring assembly that employs two separate chainrings held on to onespline using only one fastener. In so doing, the chainring assembly canbe built at a lower cost than is found in many conventional chainringassemblies while still meeting or exceeding conventional chainringassembly strength and stiffness criteria. Moreover, each of thechainrings can be individually or jointly replaced due to wear,different gearing ratios, personal preference, terrain being traversed,riding requirements, or the like.

By allowing either chainring to take part of the torque from the otherchainring utilizing the spline on the chainring assembly interface, amore robust chainring assembly interface is provided. Moreover, due tothe stacking or nesting of the two chainrings, the amount of centralmovement between the two chainrings is limited and, as such, a robustand stronger way of transferring the torque from the crank onto eitherchainring and then on to the roller chain is provided.

Further, deviation in a radial alignment of the two chainrings isdetrimental to shifting performance. However, in one embodiment, due tothe stacking or nesting of the two chainrings, the radial alignmentbetween the two chainrings is maintained. Maintaining radial alignmentbetween the two chainrings is important for shifting performance, e.g.,when the roller chain is shifted between the two chainrings.

Operation

FIG. 1A is an exploded view of a crank assembly 10, in accordance withan embodiment. In one embodiment, crank assembly 10 is shown inconjunction with bicycle frame and bottom bracket portion 11 where it ismounted. Crank assembly 10 includes a left hand non-drive crank assembly35 which includes a left hand crank arm 15 b and a spindle 12 having aspindle interface 13. Crank assembly 10 also includes a right hand driveside crank assembly 36 which includes a drive side crank arm 15 a, afastener 100, a first chainring 105, and a second chainring 110. In oneembodiment, drive side crank arm 15 a includes a chainring assemblyinterface 17 (having a number of splines 17 n thereon) and a spindleinterface 18. Examples of fastener 100 include, but are not limited to,a lock ring, a plurality of bolts arranged radially about the centralaxis of the crank (i.e. a bolt circle), and the like.

During assembly, fastener 100 will fixedly couple first chainring 105and second chainring 110 with chainring assembly interface 17 of righthand drive side crank arm 15 a thereby forming the right hand drive sidecrank assembly 36. Spindle 12 is inserted through bicycle frame bottombracket portion 11 and spindle interface 13 couples with spindleinterface 18 on right hand drive side crank assembly 36. In oneembodiment, crank assembly 10 includes one or more additional parts suchas, but not limited to, pedals, a pedal washers, a preloader, dust caps,spindle spacers, bearings, hex nuts, preload adjusters, and the like.However, those parts are not shown for purposes of clarity.

In one embodiment, first chainring 105 has a first diameter and aplurality of teeth about an outer perimeter thereof. In one embodiment,first chainring 105 has 34 teeth. Although 34 teeth are described in oneembodiment, the technology is well suited to the use of various othernumbers of teeth such as 28, 30, 38, or the like. In one embodiment,first chainring 105 is comprised of a first material. In one embodiment,the first material is a metallic component, e.g., aluminum, titanium,steel, or the like.

First chainring 105 includes a (first) center assembly shape 105 ahaving an inner diameter. In one embodiment, center assembly shape 105 adiffers depending upon the engagement method between first chainring 105and chainring assembly interface 17. In one embodiment, center assemblyshape 105 a is used to transfer the load (or torque) from crank assembly10 to first chainring 105 and then on to the roller chain.

In one embodiment, second chainring 110 has a second diameter, differentthan the diameter of first chainring 105, and has a plurality of teethabout an outer perimeter thereof. In one embodiment, second chainring110 has 24 teeth. Although 24 teeth are described in one embodiment, thetechnology is well suited to the use of various other numbers of teethsuch as 20, 14, 10, or the like. In one embodiment, second chainring 110is made from the same material as first chainring 105. In anotherembodiment, first chainring 105 and second chainring 110 are made fromdifferent materials.

Second chainring 110 includes a (second) center assembly shape 110 ahaving an inner diameter. In one embodiment, center assembly shape 110 adiffers depending upon the engagement method between second chainring110 and chainring assembly interface 17. In one embodiment, centerassembly shape 110 a is used to transfer the load (or torque) from crankassembly 10 to second chainring 110 and then on to the roller chain.

Referring now to FIG. 1B, a close up side view of drive side crank arm15 a with chainring assembly interface 17, splines 17 n, and spindleinterface 18 is shown in accordance with an embodiment. In FIG. 1B, anaxis A-A is shown. In addition, a circumference 44 and an axial length34 of chainring assembly interface 17 are shown in orientation with theaxis A-A.

With reference now to FIG. 2A, an exploded view of a chainring assembly200 having all splines engaged by each chainring is shown in accordancewith an embodiment. Chainring assembly 200 includes right hand driveside crank arm 15 a, chainring assembly interface 17, a first chainring205 having a (first) center assembly shape 205 a, a second chainring 210having a (second) center assembly shape 210 a, and fastener 100.

Referring also to FIG. 2B, a cross-section view 250 of the chainringassembly 200 of FIG. 2A is shown in accordance with an embodiment. Inchainring assembly 200, all splines 17 n about chainring assemblyinterface 17 are engaged by first chainring 205 and second chainring210. For example, in chainring assembly 200 center assembly shape 205 aof first chainring 205 uses a first portion of available axial length 34of chainring assembly interface 17 and center assembly shape 210 a ofsecond chainring 210 uses a second portion of available axial length 34such that both first chainring 205 and second chainring 210 make contactwith splines 17 n about the full circumference 44 of chainring assemblyinterface 17. In so doing, the torque is distributed directly from crankassembly 10 to each of first chainring 205 and second chainring 210separately.

With reference now to FIG. 3A, an exploded view of a chainring assembly300 having all splines 17 n engaged by first chainring 305 is shown inaccordance with an embodiment. Chainring assembly 300 includes righthand drive side crank arm 15 a, chainring assembly interface 17, a firstchainring 305 having a center assembly shape 305 a, a second chainring310 having a center assembly shape 310 a, and fastener 100.

Referring also to FIG. 3B, a cross-section view 350 of the chainringassembly 300 of FIG. 3A is shown in accordance with an embodiment. Inchainring assembly 300, all splines 17 n about chainring assemblyinterface 17 are engaged by first chainring 305. For example, inchainring assembly 300 center assembly shape 305 a of first chainring305 uses the available axial length 34 of chainring assembly interface17 around the entire circumference 44.

Moreover, center shape 305 a of first chainring 305 has an outerdiameter of splines 305 b (e.g., a secondary chainring interface). Assuch, when a second chainring 310 is utilized, the center assembly shape310 a of second chainring 310 makes contact with splines 305 b insteadof contacting the splines 17 n of chainring assembly interface 17. In sodoing, the torque is always transferred through the first chainring 305.Thus, when the second chainring 310 is utilized, the torque istransferred from crank assembly 10 to first chainring 305 and then intosecond chainring 310 through the secondary chainring interface, e.g.,splines 305 b of first chainring 305.

With reference now to FIG. 4A, an exploded view of a chainring assembly400 having a first circumferential portion of circumference 44 ofsplines 17 n engaged by both first chainring 405 and second chainring410 together and a remaining circumferential portion of circumference 44of splines 17 n engaged only by first chainring 405 is shown inaccordance with an embodiment. Chainring assembly 400 includes righthand drive side crank arm 15 a, chainring assembly interface 17, a firstchainring 405 having a center assembly shape 405 a, a second chainring410 having a center assembly shape 410 a, and fastener 100.

Referring also to FIG. 4B, a cross-section view 450 of the chainringassembly 400 of FIG. 4A is shown in accordance with an embodiment. Inchainring assembly 400, a first circumferential portion of circumference44 of splines 17 n of chainring assembly interface 17 are engaged byboth first chainring 405 and second chainring 410 together and aremaining circumferential portion of circumference 44 of splines 17 n ofchainring assembly interface 17 are engaged only by first chainring 405.For example, in chainring assembly 400 center assembly shape 405 a offirst chainring 405 has a number of depth features 405 b sectionstherein. As such, some sections of center assembly shape 405 a uses theentire axial length 34 of chainring assembly interface 17, while othersections of center assembly shape 405 a only use a first portion ofavailable axial length 34 of chainring assembly interface 17.

Center assembly shape 410 a of second chainring 410 has a number of armtype features that fit within the depth features 405 b sections ofcenter assembly shape 405 a that use only the first portion of availableaxial length 34. As such, the arm type features of center assembly shape410 a use a second portion of available axial length 34 such that centerassembly shape 405 a of first chainring 405 makes contact with splines17 n about the full circumference 44 of chainring assembly interface 17while center assembly shape 410 a of second chainring 410 makes contact417 with only a portion of splines 17 n about the circumference 44 ofchainring assembly interface 17 at depth features 405 b. In so doing,the torque is proportionally distributed from crank assembly 10 to eachof first chainring 405 and second chainring 410 proportional to thesurface area of splines 17 n engaged by each chainring.

With reference now to FIG. 5A, an exploded view of a chainring assembly500 having a first circumferential portion of circumference 44 ofsplines 17 n of chainring assembly interface 17 engaged by a firstchainring 505 and a remaining circumferential portion of circumference44 of splines 17 n of chainring assembly interface 17 engaged by asecond chainring 510 is shown in accordance with an embodiment.Chainring assembly 500 includes right hand drive side crank arm 15 a,chainring assembly interface 17, a first chainring 505 having a centerassembly shape 505 a, a second chainring 510 having a center assemblyshape 510 a, and fastener 100.

Referring also to FIG. 5B, a cross-section view 550 of the chainringassembly 500 of FIG. 5A is shown in accordance with an embodiment. Inchainring assembly 500, a first circumferential portion of circumference44 of splines 17 n of chainring assembly interface 17 are engaged by acenter assembly shape 505 a of first chainring 505 and the remainingcircumferential portion of circumference 44 of splines 17 n of chainringassembly interface 17 are engaged by a center assembly shape 510 a ofsecond chainring 510. For example, in chainring assembly 500 centerassembly shape 505 a of first chainring 505 has a number of arm typefeatures that use the entire available axial length 34 across only aportion of circumference 44 of chainring assembly interface 17.

Similarly, center assembly shape 510 a of second chainring 510 has anumber of arm type features that use the entire available axial length34 across only a portion of circumference 44 of chainring assemblyinterface 17. However, the arm type features of center assembly shape510 a of second chainring 510 are offset from the arm type features ofcenter assembly shape 505 a of first chainring 505. As such, the armtype features of center assembly shape 505 a mesh with the arm typefeatures of center assembly shape 510 a such that the combination ofcenter assembly shape 505 a and center assembly shape 510 a results incomplete contact 518 with splines 17 n about the full circumference 44and across the entire axial length 34 of chainring assembly interface17. In so doing, the torque is proportionally distributed from crankassembly 10 to each of first chainring 405 and second chainring 410proportional to the surface area of splines 17 n engaged by eachchainring.

With reference now to FIG. 6A, an exploded view of a chainring assembly600 having an entire circumferential portion of circumference 44 ofsplines 17 n of chainring assembly interface 17 engaged by a firstchainring and a remaining axial space of axial length 34 of chainringassembly interface 17 filled by a second chainring 610 without thesecond chainring 610 engaging any portion of the splines 17 n is shownin accordance with an embodiment. Chainring assembly 600 includes righthand drive side crank arm 15 a, chainring assembly interface 17, a firstchainring 605 having a center assembly shape 605 a, a second chainring610 having a center assembly shape 610 a, and fastener 100.

Referring also to FIG. 6B, a cross-section view 650 of the chainringassembly 600 of FIG. 6A is shown in accordance with an embodiment. Inchainring assembly 600, a first circumferential portion of circumference44 of splines 17 n of chainring assembly interface 17 are engaged byboth first chainring 605 and second chainring 610 together and aremaining circumferential portion of circumference 44 of splines 17 n ofchainring assembly interface 17 are engaged only by first chainring 605.For example, in chainring assembly 600 center assembly shape 605 a offirst chainring 605 has a number of depth features therein. As such,some sections of center assembly shape 605 a uses the entire axiallength 34 of chainring assembly interface 17, while other sections ofcenter assembly shape 605 a only use a first portion of available axiallength 34 of chainring assembly interface 17.

Center assembly shape 610 a of second chainring 610 has a number of armtype features that fit within the depth features 605 b sections ofcenter assembly shape 605 a that use only the first portion of availableaxial length 34 of chainring assembly interface 17. In one embodiment,the arm type features of center assembly shape 610 a fit within thedepth features 605 b sections and use the second portion of availableaxial length 34 of chainring assembly interface 17. Moreover, the armtype features of center assembly shape 610 a fit within the depthfeatures 605 b sections without engaging splines 17 n of chainringassembly interface 17.

In other words, second chainring 610 is fixed rotationally to firstchainring 605 using assembly features (e.g. press, taper, or slip fit)to ensures radial and also rotational alignment between the twochainrings without the use of extra hardware. As such, second chainring610 is located radially by spline interface without any torque beingtransmitted from splines 17 n to second chainring 610. Instead, becauseof 605 b, all torque is transmitted from crank assembly 10 though firstchainring 605 via splines 17 n of chainring assembly interface 17. Assuch, when second chainring 610 is in use, the torque is transmittedthrough crank assembly 10, into first chainring 605 and then into secondchainring 610.

Thus, embodiments described herein provide a chainring assembly thatemploys two separate chainrings held on to one spline using only onefastener. In so doing, the chainring assembly can be built at a lowercost than is found in many conventional chainrings while still meetingor exceeding conventional chainring assembly strength and stiffnesscriteria. Moreover, each of the chainrings can be individually orjointly replaced due to wear, different gearing ratios, personalpreference, terrain being traversed, riding requirements, or the like.

By allowing either chainring to take part of the torque from the otherchainring utilizing the axial length and/or circumference of the splineof the chainring assembly interface, a more robust chainring assemblyinterface is provided. Moreover, due to the stacking or nesting of thetwo chainrings, the amount of central movement between the twochainrings is limited and, as such, a robust and stronger way oftransferring the torque from the crank onto either chainring and then onto the roller chain is provided.

Further, deviation in a radial alignment of the two chainrings isdetrimental to shifting performance. Thus, in one embodiment, due to thestacking or nesting of the two chainrings, the radial alignment betweenthe two chainrings is maintained. Maintaining radial alignment betweenthe two chainrings is important for shifting performance, e.g., when theroller chain is shifted between the two chainrings.

In one embodiment, depending upon the type of bicycle being used thediameter of the chainrings can be larger or smaller and the diameter ofthe chainring is directly proportional to chainring flex. For example,in a mountain bike, trick bike, BMX bike, or the like, the chainringsnormally have a smaller diameter (e.g., 2-5 inches) to keep the groundclearance at a maximum. The small diameter of the chainrings helps limitany chainring flex even when the chainrings are fixed in place with asingle central fastener or a plurality of radial located fasteners at acentral area thereof.

However, in the case of a road bike or other type of bicycle that isused in an environment where ground clearance is not as big of a concernas top speed, it is possible that one or both of the chainrings could belarger in diameter (e.g., 6-10 inches or more). If one or both of thechainrings are large in diameter, there could be some amount ofchainring flex due to the chainrings being fixed in place with a singlecentral fastener or a plurality of radial located fasteners at a centralarea thereof. As such, at least one connection of some type between thetwo chainrings at a location further from the central axis of thechainrings could be useful to reduce chainring flex. The at least oneconnection could be at least one removably coupleable connection betweenthe two chainrings such as an adhesive, or it could be at least onefixedly coupleable connection between the two chainrings such as one ormore rivets, welds, bolts, screws, or other fasteners.

The foregoing Description of Embodiments is not intended to beexhaustive or to limit the embodiments to the precise form described.Instead, example embodiments in this Description of Embodiments havebeen presented in order to enable persons of skill in the art to makeand use embodiments of the described subject matter. Moreover, variousembodiments have been described in various combinations. However, anytwo or more embodiments could be combined. Although some embodimentshave been described in a language specific to structural features and/ormethodological acts, it is to be understood that the subject matterdefined in the appended claims is not necessarily limited to thespecific features or acts described above. Rather, the specific featuresand acts described above are disclosed by way of illustration and asexample forms of implementing the claims and their equivalents.

What is claimed is:
 1. A bicycle chainring assembly comprising: a driveside crank arm comprising a chainring assembly interface having aplurality of splines thereon, the chainring assembly interface having acircumference and an axial length; a first chainring having a firstouter diameter and a first center assembly shape, the first outerdiameter having a plurality of teeth thereon; a second chainring havinga second outer diameter and a second center assembly shape, the secondouter diameter having a plurality of teeth thereon, the second outerdiameter being different than the first outer diameter; a singlefastener to couple the first chainring and the second chainring with thechainring assembly interface, such that at least one of the first centerassembly shape or the second center assembly shape engages with theplurality of splines, wherein the first center assembly shape engageswith the plurality of splines about the circumference of the chainringassembly interface over a first portion of the axial length; and thesecond center assembly shape engages with the plurality of splines aboutthe circumference of the chainring assembly interface over a secondportion of the axial length.
 2. The bicycle chainring assembly of claim1, wherein the first chainring comprises a material selected from thegroup consisting of: aluminum, a titanium, and steel.
 3. The bicyclechainring assembly of claim 1, wherein the second chainring comprises amaterial selected from the group consisting of: aluminum, a titanium,and steel.
 4. The bicycle chainring assembly of claim 1, wherein thefirst chainring is comprised of a first material and the secondchainring is comprised of a second material different than the firstmaterial.
 5. The bicycle chainring assembly of claim 1, furthercomprising: at least one removably coupleable connection between thefirst chainring and the second chainring at a location other than thelocation of the single fastener.
 6. The bicycle chainring assembly ofclaim 1, further comprising: at least one fixedly coupleable connectionbetween the first chainring and the second chainring at a location otherthan the location of the single fastener.
 7. A bicycle chainringassembly comprising: a drive side crank arm comprising a chainringassembly interface having a plurality of splines thereon, the chainringassembly interface having a circumference and an axial length; a firstchainring having a first outer diameter and a first center assemblyshape, the first outer diameter having a plurality of teeth thereon; asecond chainring having a second outer diameter and a second centerassembly shape, the second outer diameter having a plurality of teeththereon, the second outer diameter being different than the first outerdiameter; a single fastener to couple the first chainring and the secondchainring with the chainring assembly interface, such that at least oneof the first center assembly shape or the second center assembly shapeengages with the plurality of splines, wherein the first center assemblyshape comprising: a circumferential portion that engages with theplurality of splines about the circumference of the chainring assemblyinterface; and a plurality of depth features formed within saidcircumferential portion, the circumferential portion not having theplurality of depth features covering the plurality of splines over anentire axial length, and the circumferential portion having theplurality of depth features covering a portion of said plurality ofsplines over only a first portion of the axial length; and the secondcenter assembly shape comprising: a plurality of arm type features thatalign with the plurality of depth features of the first center assemblyshape, the plurality of arm type features engage with the first centerassembly shape but do not engage any portion of the plurality of splinesabout the circumference of the chainring assembly interface.
 8. Thebicycle chainring assembly of claim 7, wherein the first chainringcomprises a material selected from the group consisting of: aluminum, atitanium, and steel.
 9. The bicycle chainring assembly of claim 7,wherein the second chainring comprises a material selected from thegroup consisting of: aluminum, a titanium, and steel.
 10. The bicyclechainring assembly of claim 7, wherein the first chainring is comprisedof a first material and the second chainring is comprised of a secondmaterial different than the first material.
 11. The bicycle chainringassembly of claim 7, further comprising: at least one removablycoupleable connection between the first chainring and the secondchainring at a location other than the location of the single fastener.12. The bicycle chainring assembly of claim 7, further comprising: atleast one fixedly coupleable connection between the first chainring andthe second chainring at a location other than the location of the singlefastener.